Field
These inventions relate to ballasts and ballasts with battery backup circuits, for example ballasts with battery backup circuits integral with or contained within the main ballast package.
Related Art
Battery backup ballasts are mandated by building codes in many geographic areas. They have the function that if there is ever a power outage, energy from a storage battery will provide some light to the facility, usually for a period of two hours, to allow people to safely exit the facility.
Conventionally these emergency battery backup ballasts are shipped with the battery disconnected. When they are assembled into a fixture, the final assembly is usually done actually on the premises which are to be serviced. With the fixture disassembled, the battery is connected to the ballast. Since the fixture is disassembled at this stage, usually with the lamps removed, the emergency ballast will start trying to strike a non-existent lamp, which may involve the production of starting voltage pulses of as much as 1500V. The subsequent assembly of the fixture can be a dangerous procedure which is routinely done by a licensed electrician. There is a need for a battery backup product which has the property that it can be shipped fully assembled, and only when it has been once connected to a power circuit and the power has been applied does it commence its normal emergency lighting function.
U.S. Pat. No. 5,811,938 describes a battery backup ballast which has a battery to provide power to light one of the lamps in case of emergency. However the product activates as soon as the battery is connected, and in addition the power applied to the lamp is DC, which seriously degrades the lamp over even a short period of time.
U.S. Pat. No. 6,876,159 describes the use of AC power to operate lamps in emergencies using AC, however this circuit will commence trying to start the lamps as soon as the battery is connected.
U.S. Pat. No. 7,084,582 describes a battery backup ballast which runs the lamps using AC, and also provides a universal input voltage feature which allows the product to operate off any line voltage from 120V to 277V.
U.S. Pat. No. 7,880,391 shows a battery backup ballast incorporating a delay between the change of AC power from on to off and the triggering of emergency lighting operation, so that the lights will not flash rapidly on and off if the power line voltage fluctuates noisily.
U.S. Pat. No. 7,965,494 connects the ballast and the battery with a set of connectors that can be snapped together, facilitating the changing of either the ballast part or the battery part of a fixture.